High Voltage PWM Rectifiers-Nine-Level NPC VSI Cascade. Application to the Speed Control of the PMSM F.Bouchafaa 1 , E.M.Berkouk 2 , M.S.Boucherit 2 Zaimeddine 1 1 Laboratoire En Instrumentation et génie des systèmes U.S.T.H.B BP N°32 EL-Alia Beb-Ezouar Alger ALGERIA Fax:(213)21.67.82.74. E-mail: Bouchafa_f@Yahoo.fr 2 Laboratoire de commande des processus. Ecole Nationale Polytechnique d'Alger-10, rue Hassen Badi, El Harrach, Alger, BP 182, ALGERIA, Fax:(213)21.52.29.73. E-mail:emberkouk@Yahoo.f Abstract - This paper describes the analysis and simulation of a cascade constituted by three phases two-level PWM rectifier-nine-level NPC voltage source inverter (VSI). This cascade is used to feed a permanent magnet synchronous machine with a speed control. In the first part, the authors present, a topology of nine-level NPC VSI for then they propose a model of this converter and the algebraic modulation strategy to control it. Then in the second part, we study the two-level PWM rectifier is controlled by a hysteresis strategy. The study of this cascade shows that the input DC voltages of the inverter are not stable. To remedy to this problem, the authors propose to introduce in the cascade a clamping bridge. The use of this strategy has let to stabilize the input DC voltages. In the last, we present the field oriented control of a PMSM. The results obtained are full of promise to use the inverter in high voltage and great power applications as electrical traction. 1. -INTRODUCTION A serious constraint in a multilevel inverter based drive is the capacitor voltage balancing problem. Depending on the drive configuration. The DC link voltages can be balanced using alternate strategies. We think to use one PWM rectifier to feed the nine-level NPC VSI. For this reason, we propose to study the cascade: one PWM rectifier-nine-level NPC VSI applied to the PMSM drive. Preliminary, we remained the knowledge model of the multilevel inverter, and its control one. Next, we present the two-level PWM rectifier. We have chose a hysteresis strategy to control this rectifier in order to have a sinusoidal network current and an unity power factor. After hat, we show some of important results of the cascade. These results are not satisfactory. Such that the input DC voltages of the nine-level inverter are not stables. Thus, let to think at a solution for this problem, we propose to introduce a claming bridge in this cascade. The results obtained are full of promise to use this inverter in high voltage and great power applications as electrical traction. 2. – MODELLING AND PWM STRATEGIES OF THE NINE-LEVEL NPC VSI: 2.1 – Nine-level NPC voltage source inverters model The nine-level NPC inverter (VSI) is a new structure of power conversion used to feed great power AC loads. Figure 1 presents the structure of the three phases nine- level NPC inverter . N T 15 Id8 Id7 Id6 Id5 Id0 I d1 Id2 Id3 Id4 Uc 3 Uc 2 Uc1 Uc5 Uc6 Uc7 Uc 4 V C V A V B M Uc8 A DD11 I 1 T 16 D16 DD 10 T 12 D 12 T 18 D18 T 11 D 11 T 113 D113 T 13 D 13 T 112 D 112 T 14 D 14 T 111 D 111 D 15 T114 D 114 T19 D19 T 115 D115 T 17 D17 T116 D116 T110 D 110 B DD21 I2 T26 D26 DD 20 T 22 D22 T 28 D28 T 21 D21 T213 D213 T 23 D23 T213 D212 T 24 D24 T211 D 211 T 25 D25 T214 D 214 T 29 D29 T215 D 215 T 27 D27 T216 D 216 T 210 D210 C DD 31 I3 T 36 D36 DD 30 T 32 D32 T 38 D38 T 31 D31 T313 D313 T 33 D33 T 312 D312 T 34 D34 T 311 D 311 T 35 D35 T314 D 314 T 39 D39 D 315 T 37 D37 T316 D 316 T 310 D3 T 315 Fig.1. Three phases nine-level NPC VSI Configuration SPEEDAM 2004 June 16th - 18th, CAPRI (Italy) 687